import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int count = 0;
        while (a > 0 && b > 0) {
            int aa = a % 2;
            int bb = b % 2;
            if (aa == 0 && bb == 1) {
                count++;
            } else if (aa == 1 && bb == 0) {
                count = 0;
                break;
            }
            a /= 2;
            b /= 2;
        }
        if (count == 0) {
            System.out.println(0);
        } else {
            System.out.println((long)(Math.pow(2, count - 1)));
        }
    }
}